The present disclosure relates generally to the field of weather radar. The present disclosure relates more specifically to the field of ground clutter rejection in weather radar.
Weather radar systems are often used on-board an aircraft to sense weather and other hazards. Ground clutter rejection is utilized for many on-board radar functions including weather radar functions and terrain awareness functions. In one particular application, detecting low lying windshear can be difficult if the region of interest is embedded in strong ground clutter.
Conventionally, ground clutter rejection of about 70 dB is required to detect low-level windshear. The 70 dB ground clutter rejection can be achieved by a combination of positioning the ground clutter responses on the skirt of an antenna beam and frequency domain editing when a large antenna is utilized. In weather radar applications that use smaller antennas (diameters less than 18 inches), the antennas have to be tilted higher (less towards Earth due to their wider beam) to achieve the required ground clutter rejection. However, tilting the antenna higher reduces the signal-to-noise ratio associated with weaker weather returns from low altitude outflows, thereby requiring more rejection using frequency domain editing. In addition, as the region of space sampled by the radar beam increases in height above the ground for higher tilt values, the peak velocity of the outflow is not measured. The peak outflow must then be estimated with a model which produces uncertainties in the outflow estimation process.
Conventional methods of using frequency domain editing utilize notch filters which can cause a decrease in signal-to-noise ratio of weather returns. The decrease in signal-to-noise ratio can be particularly disadvantageous when signals of interest are associated with low reflectivity weather phenomena.
Therefore, there is a need for a weather radar system that is optimized for performing windshear detection with smaller antennas sizes. Further still, there is a need for a low cost system for and method of rejecting ground clutter. Yet further, there is a need to detect windshear at lower reflectivity levels (e.g., less than 0 dBz, such as, −20 dBz).
There is also a need for a system for and method of more accurate weather detection in an environment including ground clutter. There is also a need for a radar system for and method of more accurately rejecting ground clutter. Further, there is a need for a method of and system for detecting windshear or other hazards using smaller antennas. Further still, there is a need for a low cost, radar-based weather sensor that can detect windshear or other hazards with a small antenna in the presence of ground clutter. Yet further, there is a need for a weather sensor that is less susceptible to noise issues and ground clutter effects.